Sodium luminair



Oct. 15, 1935. c. A. B. HALVORSON 2,017,716

SODIUM LUMINAIR Filed Aug. 24, 1954 i 2 Sheets-Sheet 1 Ihvehtor': I

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Cromwell A.B.- Halvor-soh,

Oct. 15, 1935. c. A. auALvoasou 1 somuu mmmnn Y Filed Aug. 24, 19:54 2 Sheets-Sheet 2 Invehto'r: Cromwell AB. Waiver-son,

His ttor'heg.

Patented Oct. 15, 1935 sommu nmumam Cromwell A. B. Halvorson, Lynn, Mass, assignor to General Electric Company, a corporation of New York Application August 24, 1934, Serial No. 741,253

\ 4 Claims.

My invention relates to highway fighting fixtures and more particularly to lighting fixtures using elongated light sources, such as, for ex- .ample, sodium vapor discharge lamps.

It is an object of my present invention to provide a street-lighting unit for uniformly distributing the light from an elongated source of light over a predetermined area.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description, taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the accompanyin drawings, Fig. l illustrates a side view of the preferred formof my unit; Fig. 2 illustrates a front view; Fig. 3.is

another side view illustrating a part of the mounting bracket; Fig. 4 is a diagrammatic view illustrating the development of the reflectors of the unit and the approximate light distribution thereof; Fig. 5 is a modification illustrating a combination of the elongated light source with circular reflectors; Figs. 6 and '1 illustrate modiflcations in which the elongated light source is modified so that the vertical axis is greater than the horizontal axis of a cross section taken at right angles to its main axis, and Fig. 8 is a view of an elongated lamp.

The lighting unit illustrated in Figs. 1 to 4 comprises a lamp 6 which is preferably a sodium vapor discharge lamp surrounded by an evacuated flask l for conserving the heat of the lamp and maintaining its operating temperature. The lamp is mounted horizontally having its base and contacts enclosed in a casing 8. A cover 9 is provided at the back of this casing to provideto the horizontal and intersect each other and r the axis 2| the lamp 8. The surfaces i and it are terminated at the back end of the lamp by the vertically arranged flat reflector M and are joined at the front end by'a paraboloidal surface 22. As shown in the diagram, Fig. 4, the suriaces l5 and 18 are not cut ofi at their intering to project above the reflector ll.

section but are joined by longitudinal cylindrical surfaces 23 and 24 which blend into the surfaces I5 and I 6 and join in a. ridge 25 directly above the lamp 5. The surfaces 23 and 24 are so arranged that the light directly above the lamp it- 5 self is directed away from. the lamp instead of back into the lamp.

The reflectors l2 and i3 are arranged substantially parallel to and slightly'above the axial planes l9 and 20. They are, in the present em- 0 bodiment of my invention, shown as flat reflectors but may be curved to obtain different distribution of light. They are suspended from the reflector H by straps 26 and 21 at the forward end and are joinedto the reflector M at the rear. They are further provided with extensions 28 and 29. These extensions are at a slight angle to the vertical and provide a cut off for light tend- The light impinging uponthese extensions 28 and 29 is reflected against the surfaces 23 and Hand is thereby projected along the road surface.

The reflector i4 throws the light forward so that when the unit is mounted at the side of the road with the axis of the lamp transverse thereto, the light will be thrown forward across the road- The light ditribution of the lamp is shown by curves a, b and c in Fig. 4. Curve a is the photometric curve taken in a plane vertical to the axis of the lamp. Curve b" is also taken in a-vertical'plane, but this plane is taken at a. 15 angle forward of the lamp. It will be noted that the light is thrown farther in this planethan in the preceding curve c". Curve 0" is taken in the axial planes l9 and of the parabolic cylinders.

Fig. 3 illustrates a view of the lamp from the side opposite to the one shown in Fig. l and in addition shows a portion of the supporting bracket 30.

In Fig. 5 I have illustrated a modification of my lighting unit. This unit is a combination of a circular reflector with an elongated light source. The light distribution of this unit is not as well confined as that of the unit shown in Figs. '1, 2 and 3. The advantage 'of this unit is that its cost of manufacture is small compared to that of the first unit. It includes a reflector 3i, comprising a paraboloid, and a truncated cone reflector 32 suspended therefrom by straps 38. A lamp 5 and its evacuated flask I are suspended from the cone reflector by straps 3 4 and 35. The strap 36 supports the forward end of the lamp and strap 35 supports a casing 36 within which the contacts to the lamp and the contact end of the lamp and flask are supported. The relation of the cone reflector 32 to the reflector 3| is approximately the same as in the previously described unit. The light rays impinging on the reflector 3! are reflected outwardly at a slight angle to the horizontal. The cone reflector has an inner diameter which cuts off the light that would pass beyond the edge of reflector 3i and deflects this light downwardly upon the road. The center of the reflector 3i also deviates from a true parabola so as to disperse the light projected immediately upwardly from the lamp.

In Figs. 6 and 7 I have diagrammatically illustrated a combination of reflectors and light source A wherein due to the shape of the light source a desired light distribution is obtained with considerably smaller reflectors than is possible with the light source illustrated in Figs. 1 to 4. Electric discharge lamps are considerably larger than arc or incandescent lamps and a comparatively large lighting fixture is necessary to obtain the desired light distribution. In the modifications of Figs. 6 and '7, I obtain a reduction in the size of the fixture by changing the shape of the lamp so that the transverse crosssection thereof will be elongated in a vertical direction. In this manner the total light flux of the roundlamp may be retained, less light is projected by the lamp directly below the suspended light flxture, considerably more light is available for redistribution by reflectors and the reflectors can be made considerably narrower Fig. 6 discloses diagrammatically an arrange- I ment of reflectors in combination with a lamp whose cross section at right angles to its axis is elliptical and the major axis of this section is vertical. to the ground when the unit is suspended. Referring to this diagram the lamp 40 is indicated as having an egg-shaped cross section, the major axis 4| of whichis perpendicular. I prefer to distribute the cross section of the lamp in such manner that the vertical or major axis of the cross section is 1 A times to twice that of the minor axis. In this manner I am enabled to reduce the size of the entire unit and yet obtain a better light distribution than with thecircular cross section 'unit illustrated in Figs. 1 to 4. For distributing the light of this lamp 40, I provide a pair of cylindrical parabolicreflectors 42 and 43 whose line of intersection is directly above the lamp 43 and also reflectors 44, 45, 46 and 41. i

The reflectors 44 and 45 are parabolic cylinders arranged below the reflectors 42 and 43, respectively, and are provided with extensions 43 and 49. These extensions are angularly arranged with respect to the reflectors 44 and 43 so as to reflect light which would otherwise pass beyond the edge of the reflectors 42 and 43. The angle of these extensions is so adjusted that the light reflected by extension 48 passes below the reflector 45 and the light reflected by extension 49 passes below reflector 44. Additional reflectors 4t and 41 are mounted below reflectors 44 and 45, respectively. They are arranged on either side of the lamp bulb and distribute the light of the lamp immediately below the lighting unit. They may be either flat or parabolic.

In Fig. 7 I have,illustrated diagrammatically a lighting unit using the lamp illustrated in Fig. 8. This lamp comprises a tubular discharge lamp 63 5 having a relatively small diameter tube folded into a U shape and provided with a base El and heat retaining jacket 52. The light of this lamp is distributed by reflectors-42, 43, 53 and 34. Reflectors 42 and 43 are above described and reflec- 1 tors i3 and I4 are similar to 46 and 41. Both of these modifications provide a greater amount of their available light for distribution by the reflectors than is possible with the round lamp shown in Figs. l to-4. Atthe same time the size of reflec- 1g tors can be reduced since the initial distribution of the light flux by the lamp is horizontal to a great extent. This, therefore, constitutes a more practical unit both for manufacture and for maintenance.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a street lighting flxture, the combination of an elongated lamp, a pair of reflecting surfaces arranged to distribute light from said lamp on 25 a roadway in opposite directions having their 4 3 line of intersection parallel to the said lamp, a pair of reflectors suspended from said joined reflectors and arranged parallel to said lamp on the two sides thereof, and a plane reflector arranged at so one end of said lamp and perpendicular thereto.

2. In a street lighting fixture, the combination of an elongated lamp, a pair of parabolic cylinder reflectors havingtheir axial planes parallel to the axisof said lamp arranged above said lamp to dis- 35 tribute the light from said lamp along a roadway in opposite directions, a paraboloidal surface of 'to said parabolic surfaces at the opposite end ex- 5 tending from said surfaces to the lower edge of said lamp. g I

4. In a street-lighting fixture, the combination of a'gaseous discharge lamp mounted horizontally and transversely of a roadway, a pair of parabolic 55 cylinder surfaces arranged to reflect upwardly projected light from said lamp, laterally and in opposite directions along said roadway and hav ing a line of intersection parallel to said lamp, a parabolic surface of revolution joining said re- 50 flectors atone end and a vertical reflector arranged at the opposite end of said reflectors, said vertical reflector extending from the edges of said parabolic reflectors to the said lamp.

CROMWELLA. B. HALVORSON. 05 

